(a) Field of the Invention
The present invention relates to an automatic bounce device for a center stick in a pen, and particularly to a bounce device, with which a push part is provided at an opening end of a hollow pen holder. Thus, a nib part of a standardized center stick in the pen holder can be exposed for writing from a state of concealing in the pen holder by way of pressing the push part.
(b) Description of the Prior Art
A conventional bounce type of center stick in a pen is widely adopted in our daily life. As shown in FIG. 1, a prior art automatic bounce device for a center stick in a pen provides a hollow pen holder A10 and a head end of the pen holder A10 has attached a clip A11 extending outwardly therefrom. The clip A11 at an end thereof has an engaging projection A12 jutting out from an inner side thereof. A locating hole A13 is provided on the pen holder A10 corresponding to the projection A12. A lock hole A14 is located at a place near the lock hole A13 on the pen holder A10. In addition, the pen holder A10 receives a center stick A15 and the center stick A15 has a nib part A16 at an end thereof. A pair of flips A17 are opposite to each other and disposed near the nib part A16 on the center stick A15. A restore spring A18 is placed in the pen holder A10 around the center stick A15 by the flips A17. The other end of the center stick A15 contacts with a bounce device A20 and the bounce device A20 has a push head A21 to extend outward from the head end of the pen holder A10 to be pressed while in use. Furthermore, a touch post A22 on the bounce device A20 extends inward and a leaf spring hook A23 is attached to the touch post A22 in a slightly outward inclination to fit a inverse hook thereof with the lock hole A14.
Once the above said components of the prior art bounce device are assembled completely, the leaf spring hook A23 moves away from the lock hole A14 and slides into the locating hole A13 when pressing the push head A21. In this way, the nib part A16 of the center stick A15 is forced to an exposed position outside the pen holder A10. Having been pressed, the clip A11 has the projection A12 thereof to push the leaf spring hook A23 and to move from the locating hole A13, and a resilient force of the restore spring A18 moves the center stick A15 with the leaf spring hook A23 upward. In this way, the leaf spring hook A23 engages with the lock hole A14 again. However, the prior art bounce device has the following drawbacks:
1) The center stick applied in the prior art bounce device has a length limited by the length of the pen holder and by a room in the pen holder for receiving the bounce device. Therefore, the length of the center stick is shorter than a standard length (about 14 centimeters) used in an ordinary cap type pen such that a special size for the center stick used in the bounce type pen has to be made.
2) Owing to a shorter center stick, the ink contained therein is less and it results in a writing span is limited to about 1,500 meters. Thus, a utilized period becomes shorter such that it is unable to compete with the standard sized center stick. (The writing span for the standard sized center stick is around 2,500 meters.)
3) The prior art bounce device has to be fixed in the pen holder in contact with the center stick. It is not easy to be assembled and it results in a higher production cost.
The above drawbacks leads to a pen provided with the prior art bounce device having a higher price such that it is not as popular as the conventional cap type pen even if the cap on the conventional pen is lost frequently while in use. Therefore, a revised bounce device has to be developed so as to allow the length of a center stick in a pen to be identical with a standardized center stick used in the conventional cap type pen and to allow the device being simply assembled. Then, the requirements such as lengthening the writing span and lowering the production cost can be met advantageously.